The Modulation Effects Of Astrocyte On T Cell By Inflammatory Factors

The central nervous system (CNS) has been regarded as an'immunologically privileged'area for a long time, since the blood–brain barrier (BBB) and the immune suppressive microenviroments exist in CNS. This strict regulation of CNS immune reactivity is disrupted in brain injury or inflammation, in which large numbers of leukocytes are recruited to the CNS through the damaged BBB. Several evidences have shown this specific immune response in CNS play a key role in many immune diseases, such as anti-bacterium, multiple sclerosis, autoimmune cerebritis and so on. However, due to the absence of the lymphatic vessels and dendritic cells in CNS where function as antigen-presenting cells (APC) in PNS, na?ve T cells are mainly initiated in peripheral lymphoid organs and then activated T cells enter into CNS across BBB. Once these activated or primed T cells are restimulated upon encounter of the target antigen presented by local APCs, specific immune response will occur in CNS. Moreover, T cells infiltrating the CNS fail to proliferate because of short-lived and rapid apoptosis of effector T cells after restimulation, so it is very important to maintain the activated T cell response in CNS. One of the most debated and controversial issues is how and to what extent glia cells in CNS participate the stimulation and reactivation of CNS-targeted T cells.As the most population cells of brain, Astrocytes have important physiological properties as they relate to CNS homeostasis. Most people think the microglial cells present the antigen and regulate the immune effects in CNS, while the neuro-immunology function of Astrocytes was often ignored. Recently, Astrocytes were shown to express co-stimulatory molecules, produce the inflammatory factor and release the complements to anticipate the brain inflammatory disease. Astrocytes could maintain the immune homeostasis depending on the mechanical barrier of BBB and the biological barrier as well, such as the expression of immune suppressive molecules and releasing the inhibitory mediator. It suggested the Astrocytes could become the immune effector cells to join the modulation of brain inflammation. Study has shown the Astrocytes can sense the change of internal environment...